Could Kawasaki’s Square Four Have Been A World Beater?
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- Опубліковано 5 січ 2025
- The fascinating story of Kawasaki's attempt in the early 1970s to make a 750cc Square 4 production motorcycle. Thanks to @Free_Ranger_CT110 for suggesting this video.
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Translation of display notes at Kawasaki Good Times World in Kobe, Japan:
Kawasaki, which always aims to be the fastest in the world, won the title of the fastest commercially available vehicle with the air-cooled, two-stroke, three-cylinder 750SS (Mach IV) that was released in 1971. However, the power race became numerical due to market needs. In the midst of the demand for further performance improvement, the development of the SQUARE-FOUR, code number "0280", was started secretly. Kawasaki's development team aimed to exceed the Mach IV in top speed and machine perfection while maintaining the displacement and maximum output of the 750SS. It was a new challenge to pursue the performance of the entire motorcycle, rather than relying on power alone for acceleration performance and top speed. The engine adopts a compact water-cooled square 4 layout to reduce air resistance at the front, and the right front and left front and rear cylinders are integrated. It is a twin carburetor specification with an intake port connected to each, and fuel injection was also developed to match it. The 2-in-1 exhaust pipe, designed with design as a priority, has two independent pipes on the inside to prevent power loss. Development progressed smoothly and they were close to achieving their target figures, but the plan was halted in August 1973 due to US exhaust gas regulations. The ultra-high performance machine SQUARE-FOUR, nicknamed "Steak Tartare" within the company, became a phantom model that never saw the light of day.
Video links:
2014 Kawasaki Jet Ski Ultra 310LX & 310R First Ride - MotoUSA
• 2014 Kawasaki Jet Ski ...
Kawasaki H2 750 Mach IV Triple Chainsmoker - Brightside Media
• Kawasaki H2 750 Mach I...
KAWASAKI SQUARE FOUR 750 Kawasaki Good Times World - Hifumi Watanabe
• KAWASAKI SQUARE FOUR 7...
Square Four Motocycles !!! - JAWA TINO
• Square Four Motocycles...
1956 Ariel Square Four - Moto Homeless
• 1956 Ariel Square Four
Kawasaki KR 500 Frighi - Team Cipriani
• Kawasaki KR 500 Frighi
Suzuki RG500 for sale - Vintage-Motorcycles
• Suzuki RG500 for sale
Honda CB750 - The Birth of the Superbike - Brightside Media
• Honda CB750 - The Birt...
Music credit:
Ishikari Lore by Kevin MacLeod is licensed under a Creative Commons Attribution 4.0 licence. creativecommon...
Source: incompetech.com...
Artist: incompetech.com/
#classicmotorcycles #classicmotorbike #kawasaki #1970smotorcycles
Sitting in a dark room in Idaho with my laptop watching this excellent video by 3Phils. Great way to start the early morning with my Z900 5 feet from me in the foyer. Love Kawasakis. New sub.
Thank you… and thanks for subbing! I have a bit of a history with Kawasakis, I even owned a Z900 briefly, so I’m well jealous of you having one five feet away! 💚
@3Phils Happy new year to you Mr. Phil. Had an MT09 and Z900RS previous in this spot, but for some reason I really love this bike. Take good care of that cool Trident.
I shall! I’ve had a Z1000, ZX10 and an awesome ZZR1400 along the way. My Z900 was in a rather, er, ‘unfortunate’ state but if it had been in top notch condition I can see how it would have been magnificent. Easily as good as the Norton Commando I had before it and even more of a head turner. Enjoy!
I’m suffering too my friend I have a new to me Triumph sitting one room away. I’m having trouble waiting for spring but I have 20 days till my MSF class.
Counting the seconds, I bet! Here in the UK in the 1970s you could leap on anything over 250cc once you reached the age of 17 and passed a motorcycle test, which was a simple ride round the block with the examiner observing you once or twice. Those four days from my 17th until the test day were the longest of my life! Hope it all goes well for you and enjoy the Triumph! 🏍️👍
A Happy New Year to you all!
Another brilliant video, love your stuff and humour 🎉
Too kind! I always try and achieve some kind of balance between interesting info and humour… not saying it always comes off!
Thanks for another fascinating video Mr Wobbly!
Much appreciated! Hopefully we won’t run out of weird motorcycles in 2025!
Excellent review, always enjoy your videos 👍
Would've been awesome to see these running on the roads years ago 🙂
Thank you! 😊 I agree, it would have been an interesting sight on the roads. Sadly, despite an extensive search, I couldn’t find any video of it actually running. Perhaps, somewhere in Kawasaki’s archives….?
@3Phils lots of interesting bikes from the Japanese in the 70s
I do have a soft spot for the 2 Stokes too 😉
That's mad, you learn something new every day, cheers 🍻
Good little film mate, I enjoyed it cheers
Thank you!
The sound of that RG ! Beats Akraproutprout every time.
Fascinating video, and I thought I new my motorcycle history. Thank you again.
🏍️👍
Glad you enjoyed it! 🏍️👍
I had an RG500 in Skoal Bandit colours back in the '80s and wrote it off doing a Fosbury Flop over a drystone wall on it! It was a crazy machine!
All good fun as long as no-one loses an eye! I remember those Skoal Bandit colours, very striking!
Superb, as always chaps 😉
Thank you! We aspire to keeping up the standard in 2025!
Emissions laws would have made it's production a pretty short run, having larger more 2 cycle street bikes all but banned by 1978. Suzuki already had it's excellent GT750 triple, and '77 was it's last production year as carrying it into 78 would have involved a lot of work to get it to pass tightening standards. Besides, Suzuki had their excellent I4 4 stroke bikes ready to go, and 1978 showed they weren't just jumping on the bandwagon, but really making a better bike overall. Now if Kawasaki had this square four ready to go by 1972, it would have been a different story, the GT750 was a fuel hungry beast as it was, I can hardly imagine what a 1 liter two stroke would do!
Thanks for this little vid, this is a bike I had never heard of, and I've been in biking since 1980 and really into all the strange old bikes and prototypes, and I'm surprised that this bike hasn't been something big people talked about. Even in the early 70's Ducati, under contract to an American importer developed a V4 1000, the Apollo, which was to be marketed to police agencies, and outside of (an ugly) prototype, few bring it up.
Interesting about the Ducati V4. I might look into that. Cheers! 🏍️👍
Another interesting video Phils. Thanks!
FYI - UA-cam have not given me notification of the last 2 videos. Dunno who you've upset but it may be worth investigating. This channel deserves a wider audience...
Thank you! 😊 We took a short break over Christmas so there was no video last week, however we noticed a drop-off of views for the two videos in the run-up to Christmas so it’s interesting what you say about notifications. We had put it down to everyone being too busy buying and wrapping their Christmas presents but the YT algorithm is mercurial at the best of times and it’s always a mystery to us why some videos take off at the touch of a button and others splutter no matter how many times you kick them over! 🏍️👍
I once heard someone (in a TV documentary,no less) refer to the Zed One project as New York Streak! Maybe that was a reference to the prototype test rider's underwear...😊
🤣
Build what you want but you'll never build anything better than an inline Kawasaki realize that😮
In 1979 I wrenched at a Honda / Kawasaki dealer.
I liked the design of the Honda valve train, over the Kawi.
Kawasaki had a GP 500 square four I saw it at Leguna Seca in 1980's Lawson was riding it.
Well done, 🚶🚶🚶Phil's!!!
What I got outta this, is that I want an RG-500
Cheers 🍻
Me too! Happy New Year! 👍🎉
I had an RZ 500 my mate had an RG 500 that after he read Stan Stevens 2/tuning book he handmade a set of chambers for it and altered the intake block and disc valve timing so that it could draw from two carburettors at a time and pull more mixture in I remember that with a pillion passenger you could roll the throttle on in. I think maybe third or fourth gear once it was in the upper Revs and it would lift the front wheel under power.!
@3Phils I don’t think the RE5 was a wankel of a bike. I thought it was quite good.😂
🤣
Stop it! All this talk about the RG500 is making me want one! 🤣🤣🤣
Up until today, Ariel was the only square four I knew of.
And I've been around bikes for 65 years.
Well, to be fair on you, it never made it to the outside world. I was the same until someone mentioned it on our Facebook page!
@3Phils 🍺cheers🥂
That would have been an ultra-cool bike!
It would! I’d have loved to have found footage of it running so we could have heard what it sounded like, but as far as I can see there is none. I guess we’ll have to imagine that. Probably deeper but more muted than the RG500 Gamma.
A really well researched & well made video Phil! With the Dakar about to start any possibility of iconic Dakar rally bikes over the years type of video? Just a thought...
Great idea! If it comes together, you’ll be getting a credit as usual! 😊
@3Phils thanks Phil. I did post the Kwak square 4 photo on FB for you! Cheers, Darren.
You know, it was playing on my mind that the Square Four had been suggested by someone. I guess all the festive indulgence must have clogged up my ancient brain cells. Really sorry. It’s too late to change the video but I’ll head to the description right now and give credit where credit is due!
@3Phils it's OK Phil, you wouldn't have known it was me. I keep fb & my yt channel name separate. Just happy to help, no recognition is necessary. All the best
No worries, I’ve given you a guernsey in the description now because that’s the kind of chap I am!
Dude on UA-cam could make one cat is awesome. No names.
Kawasaki made some nice bikes in the 70s, and I remember spending my dinner time going down the road from where I worked to drool over the new Z900 in a dealers window, ( I met the ex dealer driving a concrete mixer a few years later at a concrete company where I was driving a tipper lorry and he told me the chap who bought it wrecked it about 6 months later) I couldn't afford one at the time and had to continue on with my 68 honda CD175, I'm sure the square 4 would have been a fast bike but would probably have suffered from bendy frame issues like many a Japanese bike at the time. I started my riding career in 69 and I've riden more than a few with the problem
Ah, the old Japanese bendy frames! Doncha miss ‘em… not! To be fair I owned a 1976 Z900 a few years ago and I was surprised at how well it handled. Almost as good as the Commando it replaced, in fact. I think, after the horror stories of the Mach IV being a ‘widow maker’, the Japanese manufacturers really sat up and took notice. It was no longer acceptable to seat their customers on the fastest machine on the planet, said machine also had some responsibility to ensure they arrived back in one piece too. 30 years later it meant I could pilot a ZZR1400 at insane speeds with complete confidence! 🏍️👍
@3Phils I own a 1980 gsx1100et suzuki which I've had since about 84, and that handles surprisingly well, not as well as my 95 honda cb1000 big one that I've owned from new but not bad, my long gone cb750 k2 was a bit twitchy and the brand new 74 CB250G5 I had landed me on my arse more than once,
I had a couple of Honda 400/4s in the 70s and I never felt unsafe on them, they seemed to handle fine. Well, by the standards of those days at least. I found if you shod them in Dunlops and bunged a couple of Hagons on the rear end they were better. Besides, a few wobbly moments seem like all part of the fun when you’re 17!
@3Phils yes I agree a lot of the problems were down to plastic tyres and crappy shocks, I PXed my 250 for a CB550F1 super sport in 76 and that came with much improved tyres but I did eventually change the shocks, it was a nice little bike unfortunately it and me got a bit bent just before Christmas that year, I spent several months in the tender care of the NHS but the bike faired a lot better and I managed to repair it all be it on a pair of crutches when I was finally chucked out of my hospital bed,happy days
I had a 550/4 too, it wasn’t the most inspiring of bikes I have to say. For whatever reason, be it the frame, the weight, or whatever it was, the thing never felt ‘right’. I got shot of it PDQ, swapping it for another 400/4. Sorry to hear about your stay courtesy of the NHS, not least because months of hospital food is never pleasant. I spent a week in a ward in the 90s, not for anything bike-related, and I was sure glad that Dominoes deliveries had been invented by then! 🍕🍕🍕
There is one chap who has a tuned RG500 Gamma engine in an RGV 250 chassis, which must be a brilliant bike to ride. That frame does look a lot more substantial that the Gamma's rather spindly looking one, although I've heard that even as standard, they don't handle too badly. Just a bit of mental reassurance to see thicker frame rails perhaps.
I was only very vaguely aware of the RG500 Gamma in the 80s. It seemed very exotic at the time, so I was rather surprised to read while I was researching this video that Suzuki sold almost 3,000 of them! I’d love to see one racing, maybe there’ll be one at the CMRC meet in September at Brands.
@3Phils I'd love to have a go on one. I had numerous 1970's two strokes, which seemed fast at the time and had anything between 50 and 80 BHP, the latter after some tuning, but they mostly all weighed as much as 1000cc bikes do now, most modern bikes having 120+BHP. The RG is more like it, with 95 ponies as standard and weight dry of 340 lbs. Shame about the prices of them now, especially as they wear out pretty fast. I do like the relative lack of maintenance though. No valves or thrashing cam chains to stress about.
Well my FTR makes around 120bhp, but the darn thing weighs 500lbs. Of course, you don’t really notice it too much when you’re forging ahead, but to be on something almost as powerful that weighs almost 200lbs less must be awesome. I presume they’re well set up for the twisties? Not that I’ve got a lazy £20k plus to spend on one!
@3Phils My SV1000N is about 40 or 50 lbs lighter than your Indian, but even at that lighter mass, I do confess that at 67 years of age, I keep doing my three times weekly 50x3 set of pressups, else I find it too much of a struggle to manhandle it in the garage. No winter riding for me nowadays though. I have the Briggs and Stratton fuel stabiliser in it, with a full tank of BP low ethanol petrol until April.
Well I’m a spring chicken compared to you! A mere 64! But I’m finding the same. All three of my bikes are 500+ pounders, and, packed into a garage, I find it’s often the last one in that comes out for the ride! I’ve brimmed my tanks with the lowest ethanol petrol I can find, got the batteries on the Optimate, and cranked the heat up to the max to keep the temperature above the dew point. Hopefully, come the first sunny spring day, I’ll be out and about! The Trident is currently closest to the door, so it’ll probably be on that. 😊
It was maintenance costs as much as emissions that doomed the 2-strokes. Ridden hard back then you got around 5000-7000 miles between top-end rebuilds. Imagine the cost of a square 4 cylinder bore and pistons done at the dealer. Yamahas had 6 incremental 0.25mm oversizes available! ...Only if you were careful and didn't seize it and wreck the bores before you got a chance to refresh. MX bikes are even worse. It's better today because of modern oil. Better means 10k miles on pistons at best. Not if you're riding the way they should be ridden... Most went about 25,000 miles before they were parked for good.
Good point well made. I only had limited experience with 2-strokes in the 70s, but what you say has rung a big bell. Thanks! 😊
Great video thank you
It’s our pleasure. 😊
Yes, *F-7,* rotary valve, 175cc. Pulled from idle up to redline.
Yamaha did make a prototype of a - and now I must be careful - transversely mounted inline four 2-stroke 750 streetbike with fuel injection. I believe it was called the GL 750. It was roughly an early TZ 750 for road use. But as far as I’m concerned an extremely pretty motorcycle and judging just by looks alone should have the possibilities of being a “world beater”.
Interesting! And I think you got all the right words in the right order to describe the engine there too! 🤣 I’ll look this one up and see if there’s enough source material to make a video about it. Thanks for the tip! 😊🏍️👍
Yep, it was gorgeous in candy colour.
Meguro's Harley and BSA models weren't copies, they were built under licence from the two companies
Thanks for pointing that out. 😊 I’m aware that the original Ws were licensed from BSA, but I was referring to the multitude of other Japanese manufacturers in the 1950s who were perhaps less scrupulous. I think I may have worded it clumsily, though, so I’m grateful for the clarification.
@3Phils like who? The only unlicenced British equipment I know of the Japanese building were the Meguro autorace 500 motors, which were a clone of the J.A.P. powered speedway bikes that had been bought from England, and even then they were well out of production by that time. There is also the story of Honda buying an F.B. Mondial, although their first race bikes shared nothing with the Mondial and it was likely just used to benchmark against.
It's a trope that's trotted out yet I've never had it proven with an example
Interesting. I like a research challenge. If it does turn out to be a trope, I’d love to make a video about it… with your help maybe?
@3Phils I guess
@3Phils Didn't Honda make a tour of Europe looking for ideas - and concluded he'd be better off coming up with his own designs?
(He was right. In 1964, compared to a Bantam or Cub, the Honda S90 was like science fiction. )
Ariel Square Four was a pretty popular bike.
They had their problems being air-cooled and it could be said that the MK2 version technically was a step backwards.
Other sq4s were the Yamaha rd500 and Suzuki gamma 500. They were mad machines but that limited sales. Hard to think 4 stroke 600cc bikes today would leave them behind at top speed.
@@richardlee2488 It was odd that Turner didn't see it needed to be liquid cooled, as he had done car engines.
@@EbenBransome only water cooled bike in those days I immediately recollect was the Scott squirrel and maybe the brough with the A7 engine.
I bet there were loads really.
Of course he could have tried and had head gasket issues. Never reached production. I seem to remember plain copper head gaskets. Air cooled engines don't instantly destroy themselves with a little gas escaping.
Yamaha also tinkered with a 4 cylinder 2 stroke, the GL750 . Another dead end , unfortunately. ☹️
I might put that on my list! Cheers!
The Suzuki rotary is an R 'E' 5, not an R5, thanks Phil....
Want one
How did those antiquated carburettors feed the front cylinders and where was allotted space for the transfer ports ... ?
Black Magic perhaps ? ( My apologies to KR snr for ripping that one off him )
Maybe that’s why they were in the process of developing fuel injection for it?
Happy new year, despite all the signs!
Square 4 and U engines - U engines are not necessarily 4 cylinder. Pedantically, a square 4 has the two crankshafts geared together and the output is taken from one of them, usually the back one. A U engine has a gear between the geared cranks where the power is taken out, and was used on some locomotives and (in W form) on the not very good DB-610 engine of WW2.
On a standard square 4 the cranks rotate in opposite directions, improving balance. Velocette did a 2 cylinder version of this with their Roarer, with the cranks inline so putting the cylinders right out in the wind. It was not a good idea.
Because of the need for separate crankcases, multicylinder 2 strokes get excessively wide quickly. A triple is about the limit. So two geared twins makes sense, though the intake plumbing is awful. I have visions of one Kawasaki design engineer turn from his drawing board to another one who is quietly swearing, and saying the Japanese equivalent of "Cheer up mate, at least it isn't a b****y Wankel!"
Ha! I knew someone would know the answer, and I had a suspicion it would be you! Thanks for explaining it, it’s yet another mechanical mystery I can tick off my list. 😊
@3Phils Thanks. I didn't get the Ural for Christmas, though, waste of time dropping hints to the kids.
Spend their inheritance! 🤣
@3Phils I'm thinking about it.
What inherentance?
Boy are my nieces in for a big surprise, they're each getting a motorcycle, they can fight over which one gets the Sportster and which one gets the Ultra.
Never knew this “U” shaped type engine ever existed.
Now you do! Great handle, by the way! 🤣
Who knew...
Just a minor point but the Japanese make transverse engines. An inline 4 is like some indians, Hendersons, Wilkinson sword, even brough superior had an austin seven engine inline with the frame in one model.
Thanks for that. I get what you say, but my excuse is that I’ve been calling them inline fours since I was a nipper! I’ll try and do better!
@3Phils funny how I totally forgot the gold wings...
Inline but just called a boxer or flat 4 or 6 . Or the cx 500 and 550.
V twin right just wrong way round?
The use of the term "inline" when describing 4 cylinder traverse mounted engines has been around a long time and is most certainly not incorrect, an inline engine is an inline engine irregardless how it's situated in a chassis, the same holds true with cars, there's been plenty of longitudinal mounted inline 4 cylinder engines in cars just the same as there's been transverse mounted ones, they're all inline engines.
Even in the aircraft world sometimes V12 aircraft engines are referred to as inline engines, and there's always someone who comes along claiming if you call them inline engines it's incorrect, actually in that world it isn't, as it's considered to be 2 inline banks (weird huh?).
Inline simply refers to the arrangement of the cylinders, not the way it's situated in a chassis.
So let me get this straight (no pun intended), the 100% correct engineering description of, say, a Honda CB750 engine would be ‘transverse mounted inline four’?
@3Phils so that also means that the typical Harley is transverse mount inline v twin. But what does that make a Moto guzzi? Or similar?
Cool
So how about a four stroke square four or square six!
Well the Ariel was a 4-stroke square four. I’m not sure there’s ever been a square (or would that be rectangular?) six. If anyone out there can tell me different, I’ll make a video about it!
@ I did a rebuild on a KR250 many years ago so the idea of two cranks is stuck in my head altho I thought the primary drives on that bike were a bit under designed.
@@sportsmancraft1 “square”six not possible
Look up the French Foran
Couldn’t find that. Any more clues? 😊
ARIEL did a square four back in the 1940's. Good for its time....
Indeed, as mentioned in the video. You did watch the video, I assume?!
It would never have been a looker...that engine looks minging.
I’m sure Mr Matsumoto would argue otherwise! I agree, it’s not conventional but as Kawasaki themselves say, they were trying to design the fastest bike in the world and the slimmer profile of a square four helped with wind resistance.
My first thought as well. That's a touring engine and an ugly looking one at that.
Suzuki RG500 1985-1989 heiress of the racing rg.
The 500 racing kawasaki is a copy of the Suzuki, Yamaha will also copy.
What is a relationship between a 2 -stroke 4 -cylinder square and a Wankel engine?
Kawasaki was also tempted by the sirens of the Wankel crook.
Kawasakis burn through spark plugs fast and the metal quality is not good. This is why Honda outsells them by a huge margin.
I have to say that’s not been my experience with the four Kawasakis I’ve owned.
Yep you are not correct. I put 80,000 miles on a KZ400. No spark plug or metal issues ever. Kawasaki 4 cylinder models going back to the original Z1 have always been durable. While Honda has a well earned reputation for building good motorcycles l could name more Honda's that had issues than l ever could Kawasaki models. I have worked in the motorcycle industry since the early 1980's and ridden since the early 1970's.
I agree. Honda and Kawasaki have been my go-to for almost five decades now. I’ve only once had issues with a newish bike and that was with a CB550/4 in the early 1980s. However, I suspect it had probably lived a horrible life in the six or seven years since it had left the factory, before I bought it. I also bought a Kawasaki Z900 around 2015 which turned out to be problematic, but lord knows what had been done to that in the previous 40 years!
@3Phils The fact that you bought a 40 year old Kz900 speaks volumes. How many high performance vehicles would last remotely that long? An engine so rugged that could be bored and stroked out to 1340cc or so for racing tells you how tough they built them.
Well quite! If it hadn’t been for a botched rebore that had been performed by an idiot a few months before I bought it, and the fact I was quoted a year’s wait to have it done properly, I’d still be riding it now! Everything else about the machine was still rock solid.